Wake County, NC

Complete 540 Construction Project

Client: North Carolina Department of Transportation (NCDOT)
Our Role: Design

Aerial image of a four-lane highway with an intersection and road crossing underneath.

Addressing transportation demands in Wake County, the North Carolina Department of Transportation’s North Carolina Turnpike Authority (NCTA) is undertaking a multi-segmented highway construction project to complete the 540 Outer Loop around the greater Raleigh area. The NCTA is constructing the Complete 540 in two phases to extend the Triangle Expressway:

Phase 1: 18 miles from the existing corridor at N.C. 55 to I-40/U.S. 70. 
Phase 2: 10 miles from I-40 to the existing I-540/I-87/U.S. 64/U.S. 264 interchange in Knightdale, providing the missing link for 540.

With Phase 1 now complete and open to traffic, the new highway will improve safety and vehicular flow, reduce congestion, and provide a more efficient route for road users. 

Our firm played a pivotal role in designing the extension from N.C. 55 Bypass to east of Pierce Olive Road (R-2721A), a critical 4.6-mile segment of Phase 1. The new, six-lane, limited-access expressway extension features a diverging diamond interchange (DDI), nine bridges, 11 single- and multi-barrel reinforced concrete box culverts, more than 2.5 miles of brick noise walls, overhead signs, all-electronic tolling gantries, and a pedestrian tunnel. At the start of the project, the team created a design-build delivery strategy for 65% of the conceptual design. This tactic shortened the project’s total timetable by enabling the completion of the final design and the acquisition of the right-of-way to occur concurrently.

Solving Traffic and Utility Challenges With Innovative and Aesthetic Features
The design team’s innovative initiative was using a DDI at the Holly Springs exit. DDIs are becoming more common due to their ability to efficiently move crossing traffic to the opposite side of the roadway. This minimizes conflict points and reduces the number of traffic signals needed to improve safety and lower collision risk compared to conventional interchanges.
NCTA also prioritized aesthetic enhancements, especially with the sound barrier walls. The project used natural brick panels instead of precast versions to improve the surrounding landscape and enhance visual appeal. Brick panels are advantageous because they are cost-effective, have aesthetic appeal, and have a positive environmental impact, utilizing sustainable materials and local sourcing.
Safeguarding Endangered Species Through Innovative Design
The Complete 540 project team prioritized ecological protection. After discovering threats to two endangered freshwater fish species, NCTA reassessed the project’s freshwater implications and created alternate design options. About $5 million of the project’s funds purchased high-quality land in the watersheds of the Neuse and Tar-Pamlico Rivers, while an additional $4.6 million funded research on aquatic species restoration and propagation.
Phase 1 presented unique ecological challenges in nearby Middle Creek and Swift Creek, habitats for the endangered dwarf wedge mussel and yellow lance mussel. The team worked with the U.S. Fish and Wildlife Service to manage biological assessments, emphasizing increasing erosion control during construction and decreasing the likelihood of stormwater spills and highway runoff. The intent was to safeguard sensitive habitats and ultimately exceed established environmental standards.
Utility Relocation
The Complete 540 project encountered several complex challenges. Colonial Pipeline, the nation’s primary petroleum supplier, crossed the project site seven times. The team partnered with Colonial Pipeline to develop detailed relocation strategies. This partnership resulted in $50 million in utility relocation costs, the largest in state history for a single project. Early coordination for the pipeline relocation work was vital before roadway construction began.
Traffic Control
Traffic management on a busy highway was challenging, particularly on Holly Springs Road and at the N.C. 55 intersection. The team’s traffic management plan included staggered lane closures and on-site detours, which improved safety and reduced interruptions while preserving a constant traffic flow during construction.

Key Features

New, six-lane, limited-access highway.
Nine new bridges.
11 single- and multi-barrel reinforced concrete box culverts.
2.5 miles of brick noise walls, overhead signs, all-electronic tolling gantries for toll lanes, and a pedestrian tunnel.

Outcomes

Increased traffic access across the Research Triangle Park area.
Improved vehicular flow.
Reduced congestion.
Protected watersheds with endangered species.
International Partnering Institute, 2026, Project of the Year Awards, Collaborative Award.
American Council of Engineering Companies of North Carolina, 2025, Engineering Excellence Awards: Transportation, Grand Award.
Roads & Bridges Magazine, 2024, Top 10 Roads, No. 1 Road
American Council of Engineering Companies, 2025, National Recognition Award.